Fond du Lac-based Mercury Marine broke ground this week on a 30,000-square-foot addition to its propeller-casting factory, a $17 million project that will allow the company to nearly double its output of stainless steel propellers.

It’s the latest in a series of infrastructure projects for the boat-engine builder. Mercury Marine has spent more than $1.1 billion on its Fond du Lac plant since 2008, according to a news release.

The expansion comes in response to the increasing popularity of high-horsepower, 4-stroke outboard motors. These market forces have led to an “unprecedented” increase in the demand for stainless steel propellers, said Dirk Bjornstad, general manger at Mercury Marine Propellers. When complete, the company’s propeller-production factory will span 90,000 square feet. Mercury Marine produces more than 400 different propellers for a variety of uses.

The general contractor on the project is Fond du Lac-based C.D. Smith Construction.

“This capital expansion will align the propeller business with our increased growth as well as position the business to gain additional market share with new best-in-class propeller designs,” Bjornstad said in a statement.